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Messages - OgreVorbis

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106
Equipment / Re: Starting a pirate radio in Spain
« on: July 16, 2018, 0016 UTC »

Dear OgreVorbis,
Thank you very much for your detailed reply, I really appreciate it.

Regarding FM, I've pretty much discarded that option as all of the FM frequencies in my city are taken and authorities are really strict on that.

On the other hand, AM is pretty empty yet available everywhere (cars, most radios...). I live in an apartment block, so the only place I would be able to set up a MW antenna would be on the rooftop, so no buring ground sticks (those metal things, sorry for the lack of vocabulary) and space could be a little bit of a problem. How big are we talking about? Would a 1/4 dipole in an inverted vee work?

I've considered shortwave and I've talked with Stretchyman about it. I don't really have the budget to spend on a powerful transmitter, so I'd be TXing low power with one of his transmitters (I'm still learning about building one and I wouldn't want to mess it up, so building one myself is not an option, currently), meaning that I maybe wouldn't be able to reach very far, yet also wouldn't make it locally due to the skip.
What do you recommend? I'm still doubting about which route to take.

Again, thank you so much for your help.
Best regards,
Diego

In terms of antennas:
For SW, an inverted V is probably my favorite because it doesn't take up too much space and only requires one support. The skywave propagation with them is also pretty good.

For MW:
I've tried a full half wave inverted V - this was huge and the local coverage was poor, but I was able to tune into myself from an SDR about 500 miles away. (This was with 300W on 1710). The local coverage was only 2 miles interestingly.
Isotron - the worst
Long wire - second worst
1/4 wave ground plane - the best (this was temporary because I had to use a balloon to raise the wire)

If you want local, you'll need a vertical antenna. I don't know how high your block is, but maybe hanging an antenna from the roof instead of trying to fit it on top would be better. The ideal situation would be if you were on the middle floor of a tall building because then you could put the center of the dipole out the window and have one leg run up to the roof and let the other hang to the ground.

EDIT: If you decide to go with MW, you're likely going to need an antenna tuner. Unless your antenna is in the middle of a field, the surrounding objects will make it not resonate at the proper frequency. There is a formula to calculate the length, but you'll find that on MW the calculation ends up being so much different than the actual length the antenna needs to be. With shortwave, as long as you have an SWR analyzer, you won't need a tuner because generally, you can just cut the ends of the V until you get it perfect.

I also really recommend that transmitter I linked to in my other post. It will work on both MW and SW, so you won't need to buy another transmitter if you change your mind. You'll need an amplifier for it though because it only makes 1mW.

You should also check out VOACAP btw. You put in your location and a few other parameters and it will give you a theoretical coverage map. You can select the frequency and do it again to see the difference in propagation.

107
Software / Re: Pitch shift idea
« on: July 15, 2018, 0147 UTC »
a better idea is to have a TX that has full audio range and use a professional sound processor to control, filter and tailor the audio to your specific desires.
obviously, loss of the audio amplitude level is greater at higher audio frequencies which is why (modified) pre-emphasis is used as an industry standard for AM broadcasting.
this is why many SWBC stations generally have their audio frequency set at 5Khz (10Khz total occupied bandwidth), audio density is greater with less bandwidth being used.

In terms of sound processing, I'm currently using an ADAU1701 DSP from analog devices. It works really well and I'd highly recommend. The DSP eval board is $200, but you can find Chinese clones of the board for cheaper on aliexpress.

It is controlled by a flow-chart type of software called SigmaStudio. It can be modified in real time to hear the changes to the audio. Cheaper and better than a pro-processor imo.
i use "stereotool", $35 USD it cost.
dont let the name fool you, this software is used on many commercial broadcasting radio stations.

I've also used that and I like it, but it lags for me sometimes with the virtual cable. I just like the solidness of a DSP - knowing it's not going to lag or fail randomly.

108
Equipment / Re: Starting a pirate radio in Spain
« on: July 15, 2018, 0127 UTC »
Another thing to keep in mind about the effectiveness of AM: You should look up what the ground conductivity is in your area. I am in the US and it is 0.5 - 1 here (i forgot what units it's in). It seems to be on average 10. If it's low, AM won't work well in your area because it travels by groundwave. This might be a good way to decide if you want to do it. The difference is huge. Where I live now, a 1kw AM station only goes 6-8 miles!!! I used to live in another part of the US and stations with 1kw can go up to 100 miles.

109
Equipment / Re: Starting a pirate radio in Spain
« on: July 15, 2018, 0122 UTC »
I would say go with shortwave or FM, but not AM (MW). Getting an effective antenna set up for AM is hard. You need a lot of space. There any many designs for shortened AM antennas, but none of them work well. You'll go farther with the same power on FM. If you do have the space for a massive antenna, then go with AM. You'll find the range to be really good if you use the right antenna. I know this from experience.

To decide between FM and shortwave, you have to think about your target audience. Is it a bunch of radio geeks from around the world, or is it the average local person?

If you want a good FM transmitter: pcs-electronics or "The Radiomaster"
If you're looking for a SW: Stretchyman or https://www.ebay.com/itm/DDS-AM-LW-MW-SW-TRANSMITTER-MODULATOR-100KHz-30MHz-AUTO-LPF-BPF/323346484122
... then you can just get an HF linear amp and you'll cover MW and shortwave with the same transmitter.

The PWMs are better, so if you looking for higher power and more efficiency, then take a look at stretchyman instead. But for low power a linear amp should be fine (and more broadband).

110
Software / Re: Pitch shift idea
« on: July 07, 2018, 0038 UTC »
a better idea is to have a TX that has full audio range and use a professional sound processor to control, filter and tailor the audio to your specific desires.
obviously, loss of the audio amplitude level is greater at higher audio frequencies which is why (modified) pre-emphasis is used as an industry standard for AM broadcasting.
this is why many SWBC stations generally have their audio frequency set at 5Khz (10Khz total occupied bandwidth), audio density is greater with less bandwidth being used.

In terms of sound processing, I'm currently using an ADAU1701 DSP from analog devices. It works really well and I'd highly recommend. The DSP eval board is $200, but you can find Chinese clones of the board for cheaper on aliexpress.

It is controlled by a flow-chart type of software called SigmaStudio. It can be modified in real time to hear the changes to the audio. Cheaper and better than a pro-processor imo.

111
Software / Re: Pitch shift idea
« on: July 07, 2018, 0033 UTC »
Just TX a wider B/W, I usually cutoff over 7KHz.

The pitch shifting kinda sounds like a very wierd idea bud!!???

Str.

Is the range compromised by that? It would be ideal, but does it have a significant impact on range or is it small enough that it doesn't really matter?

112
Software / Re: Pitch shift idea
« on: July 06, 2018, 0205 UTC »
So, I just tested it in audacity. Audacity doesn't have the feature to pitch shift only a specific range, so:
I added the track twice.
Put a high pass filter on the first one.
Pitch shifted the first one.
Then put a 2.5Khz low pass on both tracks.
Played them together.

It sounds about the same as it would if you just used an EQ to the higher frequencies. Maybe it could be done better though. This was just me messing around. You could probably optimize the pitch shift to make it better. You might get distortion if the pitch shift isn't right.

113
Software / Pitch shift idea
« on: July 06, 2018, 0020 UTC »
So I was thinking about the limitations of audio bandwidth for broadcasting. I was wondering what it would sound like if instead of filtering at something like 2-5khz (which is around the standard), you instead pitch shift down everything above that. I don't mean pitch shift everything, just what is above where the filter cuts off. What would this sound like? Clearly it would sound lower, but would it improve the quality of the music without using more bandwidth?

Also is this possible in any software (like audacity maybe)?

114
Shortwave Pirate / Re: unidentified 6810 AM 0102 UTC 5 July 2018
« on: July 05, 2018, 0313 UTC »
How was the modulation?  ;)

This is my first transmission and I don't have a PEP meter, so I just kind of winged it.

UNID 6810 AM S5 in NY

0103: Paul Basic "Cloak & Dagger" (that was a great movie back in the day)
0111: Keeno "Piano Only"
0117: Keeno "Eos"
0121: Helios "Every Passing Hour"
0126: Galimatias "Noelle's Eloquence"
0132: Tom Middleton "Serendipity"
0136: Off the air

Impressive ID. You must have used Shazam?

116
Equipment / Re: AM broadcast pirate PWM
« on: June 14, 2018, 0659 UTC »
I would tread carefully.  I've heard some no-so-glowing reviews of his builds, especially his high power stuff.  I would also like to see some spectral measurements and see if the things can meet NRSC specs for emission.

There is a reason that commercial stuff runs in the $10/watt range... Like a friend of mine used to say about, uh, large women...lots of fun, but don't get caught.

+-RH

The rig I have from him is a PWM. The first harmonic was -35-40 dB I think, but it's been a while since I looked. He's got a 250W on ebay with PWM. So the harmonics are not great, but there where no spurs I could detect. You could easily add your own LPF. Mine came with a 3 pole instead of the 4, which is probably why it's not the best. His pics showed a 4 pole though.

All the pll.gr TXs are not PWM and they're not made by the same "amhercules" guy.

After some more searching ebay, these look better:
3-8 MHz PWM: https://www.ebay.com/itm/PWM-with-DDS-Class-D-AM-Transmitter-for-80m-40m-Bands-Assembled-and-Tested/323265554444
500-1710 kHz: https://www.ebay.com/itm/PWM-with-DDS-Class-D-AM-Transmitter-Assembled-and-Tested/323261380658

117
Equipment / AM broadcast pirate PWM
« on: May 01, 2018, 0410 UTC »
Hey,
I am making this post to show some good options if you're looking to pirate on AM broadcast band and are not skilled enough for home-brewing a transmitter.

http://amhercules.blogspot.com/
https://www.ebay.com/usr/zercvic2010?_trksid=p2053788.m1543.l2754
https://www.ebay.com/usr/kleop313?_trksid=p2060353.m2749.l2754
https://www.ebay.com/usr/savvi.polyc?_trksid=p2060353.m2749.l2754

118
Broadcast Announcements / Testing CW on 14400 khz
« on: September 05, 2016, 2117 UTC »
I'm testing 15W CW on 14400 right now in east coast US. Maybe later AM.

119
General Radio Discussion / Re: Why 69xx kHz?
« on: May 03, 2016, 2015 UTC »
After some research, it looks like the actual range is 6770-7000. It seems like this band aligns with the "land mobile" band right under 40 meters. Are there any specific stations to watch out for here (other than 6903, 6913 and 6915)?

How about the "land mobile" designations above and below the 20 meter band (13.87-14MHz and 14.35-14.99MHz)? Is there anything to watch for there? Apparently the 20m band is the most popular during the day?

I plan on operating AM. What is the normal audio bandwidth for AM on shortwave. Is it the same as the broadcast band (10khz)? Can I use whatever I want? My transmitter can go up to 50khz, so I'm deciding where to filter the audio.

I know these may seem like obvious questions to some of you, but I am not a ham, and I'm new to shortwave. (I do have all the equipment (spectrum analyzer) to make sure I'm not putting out any harmonics or spurs, though.)

Thanks for all the help!

120
General Radio Discussion / Why 69xx kHz?
« on: May 03, 2016, 0055 UTC »
So I'm new to this forum, but not to pirate radio in general. I pirated before on 1710khz, but the antenna construction is hard and I never seemed to get out very far (plus the ground conductivity where I am is really bad).

Anyway, I want to try pirating on HF and I'm wondering why most people use 69xx khz because for me it would be much easier to make an antenna for around 10-15 MHz. Does anybody listen for pirates around those frequencies? Do they get out as far?

See the graph on this site: http://www.voacap.com/antennas/squeezing-decibels-out-of-dipole/

You can see that if I created an antenna for 10-15, it is very doable to get the peak gain out of the antenna based on the distance from ground. However, if I were to use 69xx, it would be very hard for me to get more than 40ft from the ground and so not much gain...

So would pirating around 10-15 be better?

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